1. Field of the Invention
This invention relates to an image sensor, and more particularly to an image sensor module and the method of forming the same.
2. Description of the Prior Art
With the spread of digital cameras, a demand for solid imaging devices has risen in recent years. The attention has recently been riveted to CMOS image sensors which can be manufactured by complementary metal-oxide semiconductors (CMOS) technology, and the unit cost of the production of which is low. The pixel section of the CMOS image sensor includes a plurality of unit pixels arranged in the form of a matrix. Each of the unit pixels includes a photodiode and a readout transistor configured to read out signal charges accumulated in the photodiode. A gate voltage generator is connected to a gate electrode of the readout transistor. A select switch switches a voltage applied to the gate electrode so as to turn on and off the readout transistor.
As aforementioned, the digital image technique has been wildly applied to image shooting instrument such as digital camera, image scanner, etc. The conventional CMOS sensor is disposed on a circuit board. The CMOS sensor has a die secured therein. The lens seat has a focusing lens for focusing the image onto the die of the CMOS sensor. Through the lens, the image signal is sent by the die to a digital processor for converting the analog signal into digital signal. The Die of the CMOS sensor is relatively sensitive to infrared ray and dust particles. If the unwanted particles are not removed from the sensor, it leads to downgrade the quality of the device. In order to achieve the purpose, the removal by manual may damage the sensitive chip. Typically, the image sensor module is formed by using a method of COB or LCC (Leadless Chip Carrier). One drawback of the COB is lower yield rate during packaging process due to particle contamination on sensing area. Besides, the drawbacks of the LCC are higher packaging cost and lower yield rate due to particle contamination on sensing area.
Further, micro lenses are optical components on semiconductors utilized as solid state imaging devices. One of the most important considerations in designing and manufacturing micro lenses is photosensitivity. One reason micro lens photosensitivity may be reduced is that the area of each micro lens has been reduced below an optimum value. The transparency is bad due to epoxy wearing out, and the potential reliability may be reduced. U.S. Pat. No. 5,514,888 for ON-CHIP SCREEN TYPE SOLID STATE IMAGE SENSOR AND MANUFACTURING METHOD THEREOF; issued May 7, 1996 to Yoshikazu Sano, et al. teaches a method for forming charge-coupled devices (CCDS) on a silicon substrate. A micro lens array is formed over the CCD array using conventional lithography and re-flow techniques.
In view of the aforementioned, the present invention provides an improved package structure to overcome the drawbacks.